Six strength indices for steel structure steel

1, power

The strength index of steel is determined by elasticity σ E, yield σ Y and tensile σ U. The design is based on the yield strength of steel. High yield strength reduces the weight of the steel structure workshop, saves steel and reduces costs. Tensile strength, σ U, is the amount of stress a steel can withstand before it is destroyed. At this time, the structure loses its performance due to large plastic deformation, but the structure has large deformation and can not meet the requirements of the structure to resist rare earthquakes. The value of σQi/σ Y can be regarded as the parameter of steel strength reserve.

2. The plasticity

The plasticity of steel usually refers to the obvious plastic deformation without fracture after the stress exceeds the yield point. The reduction of elongation δ and area ψ is the main index to measure the deformation capacity of steel.

3. Cold bending performance

The cold bending property of a steel is a measure of its resistance to cracking when it is bent at room temperature to produce plastic deformation. Cold bending of steel is a cold bending test used to test the bending and deformation properties of steel with specified bending degree.

4. Impact toughness

The impact toughness of steel refers to the ability of steel to absorb mechanical kinetic energy under impact load during impact. Measuring the impact resistance of steel to impact load is a mechanical property that may lead to brittle fracture due to low temperature and stress concentration. Generally, the impact toughness index of steel is obtained by impact test of standard specimens.

5. Welding performance

The welding performance of steel refers to the welding joint with good performance under the condition of welding process. The welding performance can be divided into two kinds: welding performance in the welding process and the welding performance in the use of performance. The welding performance in the welding process refers to the sensitivity of the weld and the metal near the weld to no thermal cracks or cooling during the welding process, so as not to produce cooling shrinkage cracks. Good welding performance means that under certain welding process conditions, the welding metal and the nearby base metal will not crack. The welding properties are the impact toughness of the weld and the ductility of the heat-affected zone. It is required that the mechanical properties of steel in the weld and heat affected zone are not lower than those of the base metal. In China, the welding performance test method for welding process is adopted, and the welding performance test method for using performance is also adopted.

6. Durability

There are many factors that affect the durability of steel. First, the corrosion resistance of steel is poor, and protective measures must be taken to prevent corrosion and rust of steel. Protective measures include: regular maintenance of paint, galvanized steel, special protective measures in the presence of highly corrosive media (e.g. acid, alkali, salt, etc.), such as the use of "anodic protection" measures to prevent coating corrosion.